Why only one....

I have one plant of tweleve that started getting yellow from the bottom to the top. At the same time the yellow leaves started to curl under from the tips. It gets the same treatmeant as the others.... check out my grow and let me know.. I think it was root rot because I was watering by drip system everyday but the bottoms of the buckets were sitting in water for a little bit but ventalation is good and the water evaporated by the next day. but I cant get any good pics to analyze. Im 3 weeks in to flowering and everyone else is happy except on gimpy? what did i do wrong?

I will see if I can get some pics up for tomarrow but I think it will be dead cuz now its all droopy.. Ive never killed a plant like this.. I think Im... gonna

post some pix of that plant i didn't c it in ur grow pix

it was cut and removed the only thing it could be is a random disease(which does happen in nature reularly anyone hear bout the oranges?) or root rot. probably the latter I cut it to remove the negative energy. All is welll

-C